Several wind tunnels covering subsonic, transonic and
supersonic flows with test section dimensions ranging from
0.15 x 0.15 m² up to 1 x 1 m² and two water tunnels, one of
which is a closed circuit water tunnel with a test section of
1 x 1.5 m² at a maximum velocity of 4 m/s, are available.
Moreover, a test rig for certification of safety valves at a
maximum pressure of 100 bar is set up.
|
|
|
Test section with adaptive walls of the trisonic wind tunnel.
|
Color schlieren picture of the supersonic flow past a
space transportation system in the trisonic wind tunnel.
|
The experimental flow analysis is based on conventional and
up-to-date measuring techniques. Two- or three-dimensional
density distributions are determined using Mach-Zehnder
interferometry or holographic interferometry. Classical optical
methods like the shadow, schlieren, and color schlieren
technique are used to visualize flow phenomena such as
shock waves, shock boundary-layer interactions, and
separations. Various specifications of the particle-image
velocimetry (PIV) method are applied to measure velocity
distributions of internal and external flow problems. For
example, using holographic PIV the three-dimensional
unsteady velocity field within the cylinder of a 4-valve piston
engine during intake and compression stroke could be
determined. The objective of the project was the analysis of
the evolution of the vortical flow field and its impact
on mixing, i.e., on fuel consumption and pollution.
Classical techniques to measure pressure
distributions and velocities at single characteristic
points like laser-doppler anemometry (LDA) and hot-
wire anemometry as well as methods for flow
visualization like oil pattern and smoke techniques
are used to investigate fundamental flow phenomena and
engineering problems from areas like, e.g., car and building
aerodynamics. Heat transfer is measured using liquid crystals.
The development of robust multisensor hot-films enables to detect
phenomena like separation and transition under laboratory and
free flight conditions.
|
|
Velocity field of the in-cylinder flow of a 4-valve piston
engine during intake recorded with holographic PIV.
|
Free flight measurements using multisensor hot-film arrays
at 130 knots and an altitude of 3000 m.
|
Furthermore, multiphase flows are studied using stereoscopic
imaging techniques and digital image processing. Mass transfer,
bubble cloud dynamics and turbulence production are the
areas of main interest. High-speed recording and sample reconstruction
of multiple bubble paths are used to develop statistical models for
the turbulent flow field.
Stereoscopic imaging of bubbles rising in water to study
bubble cloud dynamics and turbulence production in
multiphase flows.
Last Update: 17:43:35 - 12.06.2009
|
